Slide 1Slide 2Slide 3Slide 4Slide 5Slide 6Slide 7Slide 8Methods and Problem Decomposition1-27-2010Opening Discussion●Minute Essay responses–Can we move the person to the house? If so, which will we see?–Static methods and calling things in the Greenfoot class.–How long should you expect to spend on interclass problems?–Does the API vary depending on the program you use? Will Greenfoot.getRandomNumber work on other programs?More comments–What is the difference between public and private?–Do you work on IcPs before class?–Should readings be done before or after the class they are listed for?–Could we pull code from Wombats to help make things happen?Writing New Methods●Last time we filled in some code in a method that was already part of the CityScape scenario.●Today we want to write some of our own methods. What type of functionality should we add to our person or our buildings?Problem Decomposition●One of the main reasons for having methods is that they allow us to break a big problem up into little pieces.●Computer Science is often about controlling complexity. Big problems are complex and therefore hard to solve.●You should always take a big problem and break it into pieces such that each piece is easy. Never solve a hard problem.Design Approaches●Top-down vs. bottom-up●Top-down–Start with the big problem and repeatedly break it into pieces.●Bottom-up–Start with little pieces you know how to do and put them together to solve bigger problems.Modulo and Integer Division●When you divide ints you get an int. Any fractional part is thrown away.●The remainder from division is given by the modulo operator, %.●We can do some fun things using these operators.●Let's make our person walk back and forth.Minute Essay●What do you think we should do with CityScape over the next few class meetings?●Remember that you will be showing off your interclass problems on Friday. If you have to miss class you should e-mail it to
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